Familiar sheet mediums include train tickets, airplane tickets, checks, cashes and the like. With the popularization of self-services, the automatic processing, such as stacking, distributing and withdrawing sheet mediums, is demanded in more and more industries and fields. For example, cash outputting mechanisms are used in the financial field to stack, convey and withdraw cashes, and ticket issuing devices are used in the railway filed to stack, convey and withdraw ticket sheets. Conventional sheet medium processing devices have the disadvantages of complex structure with numerous components and high cost. In order to address the problem above, a sheet medium processing device is disclosed in the Chinese Patent Application No. 200810027225.0, which comprises a housing; a feeding channel mounted on the housing; a hub assembly mounted on the housing and located at the outlet of the feeding channel for conveying sheet mediums to the hub assembly in a stacking and packing assembly; the stacking and packing assembly comprising a supporting plate for stacking a sheet medium received, limit lateral plates arranged at two sides of the support plate for aligning the sheet medium and a unidirectionally-rotating baffle plate arranged in a sheet medium transporting path; and a conveying component connected with the support plate for driving the support plate to convey the sheet mediums therefrom. The solution above mentioned has the following disadvantages: sheet mediums, if curved, may form an irregular alignment in the vertical direction after being stacked since no pressing device is provided above the support plate, and as a result, a blocking may easily occur at the output position when the support plate carries the sheet mediums out from the device. Therefore, such sheet medium processing device requires higher flatness of the mediums and is difficult to be applied on various types of mediums.